Exhaust systems that employ emission control elements must necessarily channel all gas flow through the emission control elements to be effective. The present invention relates only to exhaust systems that employ such emission control elements, therefore any reference to exhaust systems should be understood to refer only to exhaust systems that include emission control elements. Furthermore, the present invention relates only to exhaust systems where the emission control elements are removable, therefore any reference to exhaust systems should be understood to refer only to exhaust systems with removable emission control elements.
Emission control elements are known in the art; they include, but are not limited to, filters, two-way catalytic converters and three-way catalytic converters. Any reference to emission control elements should be understood to refer to all units, known in the art of exhaust systems, that are intended and designed to be periodically serviced or replaced, and through which exhaust gas must flow for the exhaust system to be effective.